How pressure testing works

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To conduct a hydrostatic pressure test on its gas pipelines , PG&E first obtains all needed work permits , coordinates with local agencies and provides gas to customers temporarily from an alternative source.

1. The section of pipeline to be tested is excavated , vented of gas and cut open at both ends. The inside is mechanically cleaned before testing.

2. A “test head”, a piece of pipeline with a hose at one end , is welded to one end of the underground pipe being tested. Another test head is attached to the other end of the tested section

3. The pipeline is filled with water through the hose.

4. The pipeline is pressurized to a specified pressure, much higher than normal operating pressure – for example , 600 psi if maximum allowable pressure is 400 psi.

5. The test pressure is is held and monitored for at least 8 hours.

6. Pipe sections that fail the test are replaced with new pipe that has already passed a pressure test.

7. Pipe is emptied of water , dried and returned to service.

Hydro‐Testing

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When Selecting Hydro‐testing as a means of proof testing that a system can withstand thpressure of operations it is important to understand what is applicable to the job. A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks.

Water Quality‐  when hydro‐testing stainless materials it is important that the water quality is low in chlorine content.  Cl2 (chlorine) is a very potent oxidizer (reason it kills bacteria) and therefore high levels of Chlorine may accelerate chloride corrosion of stainless steels. 304 and 304L, 321 SS may be used for “water applications” with up to 2 ppm chlorine, while 316 and 316L alloys may “take” up to 4 ppm.  During hydro‐testing it is important to confirm with the
water supplier in the area that the chlorine levels are within tolerance, this can be especially problematic during spring as there is high levels of runoff in the rivers.

When recording hydro‐tests clients may require both chart recording, pictures, as well as digital recording devices be made available.

Hydro‐Test Chart Recorder Paper are used to show the needle marks on the recorder to prove that the test was held for a designated time as well as pressure.

Digital recording devices are very useful for companies to provide charted tests that allow the client to review the test results and ensure that the time and pressure was achieved during the test.

Safety Training

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When establishing a safety program, it is important to first determine what it is that you do?  At Pepco pipe services, we are a very diverse company with many services and this makes it complicated to determine how to protect our team.  We broke this onto a flow chart where we determine the Hazards, Task  dentification, Training Required, as well as the Emergency Response Plan.

Pepco Pipe Services Day‐To‐Day Work Identification

Safety is the most important thing in the workplace and we strive to develop a plan that allows our team to understand their daily tasks, and how we can work together to improve.

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